The rest of a hearing test

The audiogram is the best-known part of a hearing test, but a full evaluation measures much more than the quietest tone you can hear. The rest of the report shows where in the ear a hearing loss comes from, how clearly speech comes through, and how the eardrum and middle ear are working.

Air and bone conduction

The O and X marks on an audiogram are air conduction thresholds. The tones come through headphones or earphones in the ear canal, so they travel the whole path: the outer ear, the eardrum and middle ear, the cochlea, and the nerve.

Bone conduction skips the first part of that path. A small vibrator rests on the bone behind the ear and gently vibrates the skull, which reaches the cochlea directly, without going through the outer and middle ear.

Comparing the two shows where a loss is:

• Air and bone thresholds match: the loss is in the inner ear or the nerve. This is sensorineural loss.
• Bone thresholds are near the top of the chart, air thresholds lower: sound reaches a healthy cochlea only when it skips the outer and middle ear. This is conductive loss, and the space between the two lines is called the air-bone gap. A gap of more than about 10 dB is usually considered meaningful.
• Both are lower, with a gap between them: mixed loss, some of each.

More symbols

Bone conduction and masking have their own marks.¹ Right ear marks are red and left ear marks are blue, as with air conduction.

Masking is the rushing noise played into one ear while the other ear is tested. A loud enough tone can cross through the skull and be heard by the opposite ear, and bone conduction crosses over almost freely. Keeping the other ear busy with noise makes sure each result belongs to the ear being tested. It matters most when the two ears hear very differently.

Speech tests

Tones show what you can detect. Speech tests show what you can understand.

Speech recognition threshold (SRT). The quietest level at which you can repeat two-syllable words like baseball and hot dog half the time. It should agree with your pure-tone average within about 10 dB, which is a check that the audiogram is accurate.²

Word recognition score. A list of single words played at a comfortably loud level, with the score given as the percentage you repeat correctly. Because the words are already loud enough to hear, this measures clarity rather than volume. Two people with the same audiogram can have very different scores, which is one reason louder isn't always clearer. The score also helps set expectations for hearing aids, and it's part of deciding whether a cochlear implant might help.

Speech in noise. Sentences played against background chatter, like a busy restaurant. A common test, the QuickSIN,³ reports an SNR loss: how many decibels louder than the noise speech needs to be for you, compared with someone with typical hearing. Up to about 2 dB is in the typical range. At 7 dB or more, noisy places and group conversations are usually very hard, and tools like remote microphones make a real difference. The audiogram doesn't predict this well, so it's worth asking for.

Middle ear tests

Tympanometry. A soft probe in the ear canal changes the air pressure slightly and measures how the eardrum moves. The result is a tympanogram, usually labeled with a letter:⁴

• Type A: the eardrum moves typically.
• Type As: it moves less than usual, as when the middle ear bones are stiff.
• Type Ad: it moves more than usual, as when the chain of middle ear bones is loose or broken.
• Type B: it barely moves. With a typical ear canal volume, this usually means fluid behind the eardrum. With a large volume, it means a hole in the eardrum or an open ear tube.
• Type C: it moves best at negative pressure, a sign that the Eustachian tube isn't equalizing pressure well.

Acoustic reflexes. A tiny muscle in the middle ear tightens in response to loud sounds. The same probe measures it, and the pattern of which reflexes are present helps show whether a problem is in the middle ear, the inner ear, or the nerve.

Tests that don't need a response

Otoacoustic emissions (OAEs). A healthy cochlea makes faint sounds of its own when it hears. A small microphone in the ear canal listens for them. They're usually absent when hearing loss is more than about 25 to 30 dB,⁵ so they're a quick way to check the inner ear.

Auditory brainstem response (ABR). Sensors on the head measure the nerve's electrical response to clicks or tones. Because it doesn't need anyone to press a button, it's used for babies and anyone who can't respond, and it's one of the two methods used in newborn hearing screening.

Loudness comfort

Some evaluations also measure your most comfortable listening level and the level where sound becomes uncomfortably loud. These guide hearing aid fitting, so that amplified sound stays comfortable even when the world gets loud.

Getting your results

In the U.S., you have the right to a copy of your records, including the full report and not just the audiogram.⁶ Ask for the speech scores and the tympanogram too. Keeping each report lets you, and anyone who treats you later, see whether anything has changed over time.